"Breeding-back" aims to restore or immitate extinct animals by selective breeding. This blog provides general information, the facts behind myths and news from various projects.

Sunday, 23 February 2014

Comparing skeletons with skeletons

I always
thought that it would be best to not compare living cattle with aurochs
skeletons or with accurate aurochs reconstructions because it actually is a)
imprecise and b) comparing apples with oranges because the skeleton of living
animals is surrounded by soft tissue attached to it, and therefore making our
comparisons less correct. Of course I am talking in reference to proportions,
muscle size, and other morphologic features such as hump size et cetera. The
best and most precise method for this is to compare osteologic material of the
aurochs to that of the breeds of interest. The problem: there are no
articulated, prepared skeletons of those. Therefore I had the idea to get an
impression how the skeleton roughly looks like by deducing it from photos of
living cattle. All you need is a pen, piece of paper and basic knowledge on the
anatomy of these animals. It’s basically the reverse of a life restoration. For
example, the M. trapezius tells you approximately where the shoulder blade
ends, in less-muscular cattle you can even see the outline of this bone through
the skin. Same with the pelvis. The elbow, knee and knuckles show where the
limb elements end. If you know a bit about the soft tissue on a cattle’s head,
you can deduce how the skull inside looks. Eye, ears and horns are a useful reference
points. I also used qualitative cattle skeleton illustrations as an aid, see
here and here.

I used
photos of 10 cattle breeds, five of which I did both bull and cow. I chose either
individuals representative for their breed or those which look very
aurochs-like from “outside” and I wanted to check if they do so on osteologic
basis. Mind that these drawings are very schematized and I only cared about
what is relevant for these comparisons, so please no complains on irrelevant
details like vertebra or rib count/shape. I messed up some of the skulls, but I
plan to do an extra skull series anyway.

For the
metric evaluations, I took the trunk length as reference again. Trunk length is
defined as the horizontal distance from the anteriormost part of the scapula to
the posteriormost part of the pelvis. Shoulder height is defined as vertical
distance between the ground and the top of the shoulder blade. In living
animals, we tend to define the shoulder height as distance from the ground to
the withers, but these comparisons are worthless because they are influenced by
the hump size, which is actually a different factor. I define the hump as the
vertical distance between the top of the shoulder blade and the top of the
shoulder spines. Again, in reference to the trunk length. However, this is not
totally precise, because it makes a difference if only a few of these spines
have that length or the complete anterior half of the trunk spine. But you have
the drawings of the skeletons from which you can see that.

So that we
know what we are comparing, I did those measurements with two representative
complete aurochs specimen, the Braunschweig bull and the Sassenberg cow (of
course I had to correct the articulation of the bones before, since virtually
all skeletons on display are mounted incorrectly):

I actually
wanted to include the perfectly-proportionated and perfectly-shaped Heck bull
Oostvaardersplassen bull as well, but the resolution is too small. Bear in mind
that these measurements provide only rough relations, as this method is surely
prone to imprecisions and is never as effective as working with real skeletons.
But I think the overall impression is sufficiently accurate. Looking at the
proportions of the skeletons, the Heck bull and the Braunvieh bull are the
least aurochs-like. The trunk is long, head small and hump non-existent, as you
see in living animals. The Heck cow has a shorter trunk, but there are more
longish ones of course, and the hump is absent. Surprisingly, the Chianina bull
has the longest trunk. This is probably the reason why first-generation Heck x
Chianina bulls usually were still long and massive. The Pajuna bull has a long
trunk, but apart from that, it’s skeleton is pretty good. The head is large and
longish, the hump is acceptable. The Taurus bull is well-proportionated as
well, except that the head could be larger. The hump is good, but could be
larger as well.

All the
other skeletons are awesome. Like I expected, the skeletons of both the Lidia
cow and bull fit the aurochs in virtually all respects – proportions, hump
size, skull size and length (bull, the cow seems to be subadult). Also their
silhouettes resemble a wild animal like the aurochs most closely. The skeletons
of both the Maremmana (belonging to Tauros Project, by the way), the Sayaguesa
cow and the Podolica are very aurochs-like as well. The hump size of that
Sayaguesa cow (Tauros Project again) is impressive. The hump of the Sayaguesa
bull (father of the Taurus bull) seems a bit too small. The skeleton of the
Maronesa cow is superb, as much as her life appearance. The Maronesa bull has a
very aurochs-like skeleton as well, if the trunk was larger it would be as
aurochs-like as the Lidia bull, apart from the head.

My
conclusion is that the osteometric features of the postcranial skeletons of the
most primitive cattle are very similar to the aurochs. According to an old
German reference, the aurochs’ bones are said to be more robust than those of
domestic cattle, probably partly due to the more strongly developed muscle
attachment areas and because they have to resist the stresses caused moving at
high speed and fighting against conspecifics and predators. I guess that this
comparison was done with very derived “usual” cattle, but I think that the
primitive breeds might be somewhere in-between, because they are still less
muscular and less tight-bodied as the aurochs probably was – with the possible
exception of the very muscular Lidia. The fact that the body of most primitive
cattle is not as athletic as that of wild animals is not all too problematic in
my opinion. The phenotypic changes in some of the cattle at OVP has shown that
the body shape gets more athletic due to living in the wild, caused by
phenotypic and probably genetic changes, even when the founding population are un-athletic
Heck cattle. The skeleton of many of the OVP cattle still has to change in order to
match the aurochs, and this will take yet more decades. Considering that Tauros
Project works with well-proportioned animals of which some have very
aurochs-like skeletons as you see above, they might surpass the current OVP Heck
cattle regarding body shape and proportions right from the beginning when the Tauros cattle are opposed to natural selection. But for that I think they have to get rid of
the Highland cattle and short-legged Limia individuals.

I didn´t read all the details, but for Maremmana, for example, I see this:

Trunk/leg length: 1:0,94Hump size: 1:9,34Head size: 0,3

Hump size should be 0,034?

And maybe, I could be wrong, because I don´t know about the scaling used, but even having this in mind, I think that the Maronesa bull in the real life picture seems to have the tip of the muzzle close to the horn tip, than on your hypothetic skeleton example and also seems to have longer back legs and front legs.

The lidia bull muzzle isn´t projected longer than the horn tips in the real life picture, I think.

Hump size in the lidia cow is 0,045?When I compared it with other examples, I see some more developed humps though with a lower score.

By some reason the Pajuna bull real life picture isn´t visible.

The Podolica hump size is that big (0,048)?

The Taurus bull is a bit with his head down and stretching his legs, so this might give a wrong idea about his hump (though I see a not bad score with 0,034, so I wonder if you had this in mind).

The Maronesa bull might look slightly different because it's in an elevated stance on the photo, I turned it to a horizontal position for the drawing. The Lidia muzzle should be ok.

The Lidia cow's hump appears a little smaller because I measured, like stated above, the distance between the end of the spines and the shoulder blade.

Yes the Podolica's hump is that big. That of the Lidia bull isn't small at all, it's the largest of all of the drawings if you take a look, and almost as big as in the real aurochs from Braunschweig. I considered that with the Taurus bull's hump indeed.

The Lidia has 0,08 because the end of the scapula and the height of the shoulder spines indicate it and that's the result of the measurement -> (distance between the shoulder blade and the end of the spines)/trunk length; what's the problem with 0,08?

About this blog

This blog is on everything related to the so-called “breeding-back” of extinct animals: From the extinct animals themselves, over their often domestic descendants and dedomestication to news and facts about various breeding-back projects, reports and photos from my own breeding-back related trips. I try to have a balanced and fact-based approach to this subject and to dismantle many of the popular myths. Enjoy!

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About me

I am an Austrian student of biology/zoology at the University of Vienna. My major interest always have been extinct animals, from dinosaurs to Pleistocene megafauna and more recent extinctions. Besides that I am interested in evolution, genetics and ecology.
I am also an amateur animal artist, making drawings and models mostly of extinct animals.